The Physical Nature and Orbital Behavior of V523 Cassiopeiae

Abstract

V523 Cassiopeiae is a dwarf contact binary with one of the shortest orbital periods among the nondegenerate systems. Its orbital history is marked by large period changes. The photometrically determined mass ratios have historically been inconsistent with those calculated from radial velocity curves. In 1998 we acquired highprecision and standardized Johnson-Cousins UBV light curves. Our simultaneous BV light curve/radial velocity curve solutions provided good fits to both the light curves and the radial velocity curves using standard gravity darkening coefficients with a mass ratio of $0.5. Seven precision mean epochs of minimum light were determined from these observations. We combine these with all available published times of minimum light, along with 50 times of low light found from a search of the archival Harvard plate stacks in the interval 1901-1942 to give us 567 eclipse timings. Our period study covers nearly 160,000 orbits, or $102 yr. We find a high-amplitude sinusoidal variation with a period of 101 AE 7 yr, overlaid on a strong continuous period increase. The quadratic term is common in contact binaries, but a sinusoidal one is not. This suggests a hierarchical three-star system. Assuming that this is the case and that the inclination from our orbital solution for the close pair is the same as the larger orbit, we obtain a mass for the third star of 0.41 M . This is similar to the masses of the stars that comprise the contact binary. If this scenario is correct, V523 Cas consists of a trio of late K and early M-type dwarfs having a total mass of $1.6 M . We show that high-resolution imaging can confirm this suggestion.

Effects of the Mass Transfer and Presence of the Third Components in Close Binary Stellar Systems

“…Mass of the third body were estimated for WZ Cyg (Lee et al, 2011) it is comparable in order of values with our estimates. For V0523 Cas our estimation of the mass of the third body is approximately 20 percent smaller than one in (Samec, Faulkner & Williams, 2004).…”

Photometric Observations of the Contact Binary System V523 Cassiopeiae

“…Samec & Bookmyer (1987) and Samec et al (1989) reviewed the early history of this system. Mass ratios produced by photometric solutions of V523 Cas are q ph = 0.59 by Bradstreet (1981), 0.571 by Samec et al (1989), 0.53 by Lister et al (2000), 0.56 by Kim & Jeong (2002), and 0.52 by Samec et al (2004). Those values disagreed with the spectroscopic mass ratio, q sp = 0.42, derived directly from radial velocity curves by Milone et al (1985).…”

“…The results of spot parameters are listed in the lower part of the 4th column of Table 5. In order to compare, the solutions by Samec et al (2004) and Jeong et al (2006) are also tabulated in the 2nd and 3rd columns of Table 5, respectively.…”

“…Since Weber (1958) discovered the light variability of V523 Cas, many investigations in photometry and spectroscopy have been carried out (Zhukov 1972, Haussler 1974, Lavrov & Zhukov 1975, Bradstreet 1981, Hoffmann 1981, Samec & Bookmyer 1987, Zhai et al 1988, Samec et al 1989, Kim & Jeong 2002, Samec et al 2004, Genet et al 2005, Jeong et al 2006. In results, some facts about V523 Cas are known: 1) its orbital period of about 336 minutes is one of the shortest among late type contact binaries.…”

“…However, an analysis of new, high-precision radial velocity curves by Rucinski et al (2003) has shown that q sp = 0.512. Samec et al (2004) found that, even with using simultaneous solution method, it is impossible to get a good fit to the light curve and the radial velocity curves. Jeong et al (2006) obtained q = 0.54 from the combined analysis of their BVRI light curves with the double-lined radial velocity curves of Rucinski et al (2003) by the Wilson-Devinney (WD) binary model.…”